It is found that the structure of trampoline support frame has also become key technology gradually in the improvement of trampoline due to a large amount of jumps and bumps generally arising when a trampoline is used by a user. For instance, China patent publication no. CN202001453 disclosed a connecting structure of trampoline frame comprising a cross rod and a vertical rod. One end of the vertical rod is provided with an annular faucet fixed to the cross rod by welding. Further, China patent publication no. CN201082327 also disclosed an improved trampoline comprising an annular frame, an elastic net, a plurality of supporting components and a plurality of retaining plates. The elastic net is provided at inner side of the annular frame. The supporting components are used for supporting at the bottom of the annular frame, respectively. In this case, each of the supporting components and the annular frame are welded together via the retaining plates so as to be fixed.
It may be found in the technical contents of above two patents, however, there is none of fixing structure between two side surfaces adjacent to the bottom of the cross rod and the vertical rod, because the vertical rod is only fixed to the bottom of the cross rod by welding in the patent no. CN202001453, which further leads to the break of the cross rod with respect to the vertical rod readily generated due to impact force during the trampoline is used. In the patent no. CN201082327, additionally, although one side of the annular frame may be fixed to the supporting component by welding via the retaining plate, there is a problem of insufficient assembling strength owing to none of fixing structure between another side of the annular frame and the supporting component. Furthermore, it may be further found, from the viewpoint of assembling process of the trampoline, that it is necessary to align the retaining plate with the supporting component and the side of annular frame after the supporting component and the annular frame are assembled, followed by fixing the retaining plate at two sides thereof to the supporting component and the annular frame by welding, respectively, via welding equipment. As a result, the increased manufacturing cost due to excessively complicated manufacturing process and the problem of environment protection, such as excessive manufacturing energy consumption, may occur in the trampoline.